The heptazine-based polymer melon (also known as graphitic carbon nitride, g-C3N4) is a promising photocatalyst for hydrogen evolution. Nonetheless, attempts to improve its inherently low activity are rarely based on rational approaches because of a lack of fundamental understanding of its mechanistic operation. Here we employ molecular heptazine-based model catalysts to identify the cyanamide moiety as a photocatalytically relevant 'defect'. We exploit this knowledge for the rational design of a carbon nitride polymer populated with cyanamide groups, yielding a material with 12 and 16 times the hydrogen evolution rate and apparent quantum efficiency (400 nm), respectively, compared with the unmodified melon. Computational modelling and material characterization suggest that this moiety improves coordination (and, in turn, charge transfer kinetics) to the platinum co-catalyst and enhances the separation of the photogenerated charge carriers. The demonstrated knowledge transfer for rational catalyst design presented here provides the conceptual framework for engineering high-performance heptazine-based photocatalysts.

中文翻译：

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通过将氰酰胺缺陷确定为催化相关位点，合理设计氮化碳光催化剂。

庚嗪基聚合物瓜（也称为石墨碳氮化物，g-C3N4）是一种有前途的氢析出光催化剂。但是，由于缺乏对其机械操作的基本了解，因此改善其固有的低活动性的尝试很少基于理性的方法。在这里，我们采用基于分子庚嗪的模型催化剂，将氰胺部分确定为光催化相关的“缺陷”。我们利用这些知识对填充有氰酰胺基团的氮化碳聚合物进行合理设计，与未修饰的甜瓜相比，所得到的材料的氢释放速率和表观量子效率（400 nm）分别为氢的12倍和16倍。计算模型和材料表征表明，该部分改善了配位（进而，电荷转移动力学）转移到铂助催化剂上，并增强了光生载流子的分离。本文介绍的合理催化剂设计的知识转移提供了工程化高性能基于庚嗪的光催化剂的概念框架。